Gemini Observatory: Exploring the Universe, Sharing its Wonders

Near-Infrared Images Reveal Structure in Jupiter's Cloudy Atmosphere

August 6, 2003

High spatial resolution NIRI images taken in the 1.69-micron methane
absorption band expose the detailed structure and varying chemistry of the clouds high in the Jovian atmosphere.

Click on image for full-resolution

The image
of Jupiter was obtained as part of a systems check for the Gemini
Near-Infrared Imager (NIRI) and was also used for a contest in which a
Canadian elementary school student selected Jupiter as a target for
Gemini. The Canadian Gemini Office located at the Herzberg Institute of
Astrophysics in Victoria, BC, together with the Canadian Gemini
Scientist sponsored a contest for Canadian school children. The aim was
to make students more aware of astronomy in general and the Gemini
Observatory in particular. Each entrant submitted a short paragraph on
their favorite object in the sky and the winners were selected on the
basis of the originality of the object and the reasons why it was their
favorite celestial object. Two prizes were awarded one for elementary
school children and one for those in high school. The prize in both
cases was an image of their object specially obtained for them by the
Gemini staff with one of the 8-meter telescopes. The high school winner
was Tracy Falukozi from Calgary for her entry "The Cat's Eye Nebula",
while the elementary winner was Julian Trombinski from East Selkirk
near Winnipeg for his entry on "Jupiter".

The planet Jupiter has dozens of very small, faint moons that have been
discovered in recent years. The Gemini 8-meter telescope has been used
to measure the properties of these moons by determining their infrared
brightness. In preparation to observe the very faint moons, Gemini
astronomers needed to make sure the telescope was tracking Jupiter
properly because all of the planets move at varying rates against the
background stars. This image of Jupiter was taken as a quick check of
all telescope systems before observing the faint moons, which might not
be obvious in individual short exposures.

Jupiter was imaged at a wavelength of 1.69 microns using the Gemini
Near-Infrared Imager (NIRI) on December 13, 2002 at 16:00 UT. This
image is a combination of 20 individual 0.4-second exposures, which
together make the equivalent of an 8-second exposure. Additionally,
three 8-second frames were collected within a few minutes. The rotation
of Jupiter is clearly apparent when the individual frames are animated.
Jupiter's period of rotation (its day) is less than 10 hours long. The
resolution in this exposure is 0.35 arcseconds (without adaptive optics
correction) and shows the excellent image quality delivered by the
Gemini telescope and NIRI.

Two of Jupiter's Galilean moons are visible in this image as well:
Europa is the bright "star" to the right of Jupiter, and Io is the
bright spot projected against the equatorial cloud bands towards the
right edge of the disk. They can be seen to move in their orbits in the
animation.

Methane
gas strongly absorbs infrared light with a wavelength of 1.69 microns.
Thus, the darker regions in this image are areas in the Jovian
atmosphere that are rich in methane. Dr. Tobias Owen (University of
Hawaii Institute for Astronomy) explains that the bright areas,
particularly near the equator, are regions where high ammonia cirrus
clouds block our view of the lower atmosphere. The Great Red Spot (the
white oval at lower left in this false-color image) is a cyclonic storm
system, which extends well above the surrounding cloud tops. The nature
of the bright haze near the poles is still not well understood, but is
probably composed of complex organic compounds produced by the intense
shower of charged particles trapped in Jupiter's strong magnetic field.

The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai'i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in five partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country's contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, the Brazilian Ministério da Ciência, Tecnologia e Inovação and the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT). The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.